Apparatus for tube manufacture



Oct. 16, 1928. 1,687,872

c. E. MAYNARD APPARATUS FOR TUBE MANUFACTURE Original Filed May 27, 1926 1 N VEN TOR.

M/fM M BY 9255;

Patented Oct. 16, 1928.

UNITED STATES PATENT OFFICE.

.cnmns EDGAR MAYNARD, rrsx RUBBER COMPANY, or unssacnusn'r'rs.

' Original application filed lay 27,

This invention relates to the production of rubber tubes such as inner tubes for automobile tircs. It has for one object the simultaneous trimming to length and skiving of the 6 ends of the tube prior to vulcanization. It has for another object the elimination of all cutting of trimmings or scra fromthe tube after vulcanization. It has ot er and further objects which will appear from the following description and claims.

This application is a division of my prior application Serial No. 111,968, filed May 27, 1926, in which is claimed the method in which the apparatus of the present case finds its principal use.

Referring to the drawings,

Fig. 1 is a'plan view of a trimming and skiving tablev embodyin my invention;

Fig. 2 is an enlarge top plan view of a I '20 portion thereof;

Fig. 3 is a side elevation of the portion of the device shown in Fig. 2;

Fig. 4 is a section on line 4-4 of Fig. 3;

Fig. 5 is a sectional detail of a rubber tube prepared for vulcanization and ready for the skiving and trimming operation;

Fig. 6 IS a similar view illustrating the completion of the skiving and trimming operation; and

Fig. 7 is a similar view illustrating amodified way of preparing the tube for vulcanization.

In the manufacture of inner tubes for automobile tires it has been customary to vulcanize the tube u on a mandrel, remove it from the mandre, skive the ends and join the tube into annular form. The urpose of the skive is to facilitate the splicing of the ends and to avoid sudden changes in thickness in the wall of the completed tube. Originally this skiving was done upon specially designed'cutting machines into which the ends of the vulcanized tubes were inserted after removal from the mandrel. More late- 5 ly it has been proposed to make the skive during vulcanization b some species of clamp or cuff which molde the end of the tube against the mandrel as the tube was being cured, as in myPatent No. 1,391,784 and in the patent to 'Little No. 1,450,320. Either of these methods necessitates the length of the tube being initially greater than that ultimately desired, with a consequent trim- OF NORTHAMPTON, MASSACHUSETTS, ASSIGNOR TO THE 0] CHICOPEE FALLS, MASSACHUSETTS, A CORPORATION APPARATUS FOR TUBE MANUFACTURE.

1088, Serial No. 111,988. Divided and this application filed Kay 9,

1827. Serial No. 190,037.

ming of the tube after it has been vulcanized. The trimming or scrap thus produced, being of vulcanized rubber and therefore being incapable of reuse without undergoing a reclaiming or desulphurizing process, is worth less to a rubber manufacturer than the same amount of scrap in unvulcanized form. Further proposals have therefore been made, by which the tube was skived by clam s or cufi'slefton during vulcanization an the tube trimmed to length prior to vulcanization either by the cufls themselves or by a knife.

These prior proposals have all been ob jectionable for one reason or another, because of extra operations involved, the production of cured scrap, or the ex ense and labor incident upon the use of c amps or cuiis. By my invention I am enabled to avoid these awkward and expensive prior methods, and to cut the tubes to length and skive them at one operation without the use of clamps'or cufi's during vulcanization. In another aspect of my invention I prepare the tubes for vulcanization in a better manner than has hitherto been done, avoiding the use of ex ensive equipment during vulcanization an of fectively preventing the formation of blemished or defective tubes by the entrance of the vuleanizing fluid between the tube and the mandrel. Stated rather briefly, my invention comprises trimming the end of the tube, while still uncured and mounted on the mandrel, by a knife shaped and mounted so as to out upon a bevel, thus skiving the tube and'cutting it to length in one operation.

I have shown in the drawings one e1nbodi-' ment of my invention in tube cutting and skiving apparatus. Upon a table 10 are $6- cured journals 11 for spaced pairs of rolls 12, these rolls serving to support rotatably a tube mandrel 13. Preferably one of these rolls carries a sprocket 14 connected by a chain 15 to a sprocket on a power shaft 16. Of course other means of rotating the rolls may be used, or the rolls may be free and the mandrel rotated upon them b hand. In case the mandrel is to be rotated y the rolls, it is preferably held against them by a roll 17 carried as on a. swinging arm 18 and pressed against the mandrel by a spring 19. Drivin means have been shown at one end only of the mandrel, but if desired it may be 106 rotated from both ends.

- against the mandrel Mounted upon a bracket 20 at each end of the table is an electric heating element 21 of any usual type, such for exam le as is employed in electrically heated so dering irons.

heavy metal heat conducting body 22 projects from this heating element and is split to receive a cutting blade 23. is preferably formed of some metal such as bronze which combines the features of high heat conductivity and Wearing qualities. The cutting edge of the blade is shaped so that at one end 24 it comes in contact with the mandrel while the other end 25 is spaced a short distance away. Intermediate these points the blade is curved both away from the mandrel surface and lon itudinally of the mandrel, so that the cut madb will be along a taper. As the mandrel revolves, the rubber tube 26 upon it is drawn past the knife which is preferably heated to a temperature suflicient to soften the rubber and facilitate the cutting. The tube is thus simultaneously cut and skived along the line 27 the trimmed end 28 being now removable, leaving the end of the tube beveled off as at 29 in Fig. 6.

As stated before, it is one ob'ect of my invention to improve the sealing of the tube to the mandrel. This is of importance in methods of tube vulcanization in which the tube is exposed to the action of a heated fluid such as steam. In this connection I make use of, and in certain aspects improve upon, the disclosure in my copending application Serial No. 102,458, filed A ril 16, 1926, in which a band of cement or ot ier adhesive rubber is applied between the tube and the mandrel. This band of rubber is indicated in the present drawings at 30. Preferably the skive is made so that it passes through the cement, the combination of the heat of the knife, the drawing or shearing nature of the cut and the pressure with which the knife is forced making a perfect seal at this point and insuring that the tube will be stuck securely to the cement As a fur ther safeguard I may place over the end of the tube a short band of vulcanized rubber 31 (Fig. 7), conveniently cut from a tube of smaller diameter than that of the mandrel 13. The band 31 need not be heavy enough to exert any skiving or sealing pressure of its own, serving merely to prevent any accidental curling or displacement of the thin edge of the tube 26 during the cure.

y using one of these cutting and skiving units on each end of the mandrel, the tube will be trimmed accurately to length and both between Having thus described my invention, I"

claim:

1. A bevelmg and trimmin knife for a rubber tube on a mandrel whic comprises a cutting edge curved to encircle with a between them, and extending helically of the mandrel, whereby when a tube drel is rotated in contact with the knife the tube will be trimmed off on a circumferential line and the end of the tube simultaneously skived.

the mandrel I'O IGSSIVGl dlmimslnn distance a y n 2. A beveling and trimming knife for a rubber tube on a mandrel which comprises acutting edge curved to encircle the mandrel with a progressively diminishing distance between them, and extending helically of the mandrel, whereby when a tube on the mandrel is rotated in contact with the knife the tube will be trimmed oil on a circumferential line and the end of the tube simultaneously skived, and means for heating the cutting edge.

3. A beveling and trimming knife for a rubber tube on a mandrel which comprises a cutting edge curved to encircle the mandrel with a progressively diminishing distance between them, and extending helically of the mandrel, whereby when a tube on the mandrel is rotated in contact with the knife; the tube will be trimmed off on a circumferential line and the end of the tube simultaneously skived, means for heating the cutting edge, and means for rotatably supporting the tube in contact with the cutting edge.

rubber tube on a mandrel which comprises a cutting edge curved to encircle the mandrel with a progressively diminishing distance them, and extending helically of the mandrel, whereby when a tube on the mandrel is rotated in contact with the knife the tube will be trimmed oif on a circumferential line and the end of the tube simultaneously skived, means for heating the cutting edge, and means for rotating the tube, mounted on the mandrel, in contact with the cutting edge.

CHARLES EDGAR MAYNARD. 

